| Digital mobile telecommunication hare been in the using situation. There are many plans about the future mobile telecommunication. TD-SCDM, WCDMA & CDMA2000 are three main technology in IMT-2000 .Although China have not determine the plan of net form ,it is clearly that China will go into 3G times . When net scale is expanding , because the limited of frequency souse ,frequency reusing radio will increase .It is important for the frequency planning of 3G and improve the utilization radio of frequency to study whether they could conexist in the neighboring frequency band and the protective band to conexist . The text is the study of TD-SCDM, WCDMA & CDMA2000 working in the neighboring frequency band and the protective band and protective distance to conexist . Supposing WCDMA and TD-SCDMA conexist in the 2500-2690MHZ,the expanded frequency band of IMT-2000. TD-SCDMA and WCDMA UL or TD-SCDMA and WCDMA Dl are working in the neighboring frequency band,There will have the following situation : (The Interference TD-SCDMA BS to WCDMA BS (The Interference TD-SCDMA BS to WCDMA MS (The Interference TD-SCDMA MS to WCDMABS ( The Interference D-SCDMA MS to WCDMA MS (The Interference WCDMA BS to TD-SCDMA BS (The Interference WCDMA BS to TD-SCDMA MS (The Interference WCDMA MS to TD-SCDMA BS (The Interference WCDMA MS to TD-SCDMA MSIn the text it is an example to study in the same area and in the neighboring frequency band The Interference TD-SCDMA BS to WCDMA BS. The other situation is similar .When working in the neighboring frequency band,the two frequenc's distance is 3.3MHz,TD-SCDMA's ACLR is 50dB, the neighboring channel select are 58dB.To study the The Interference TD-SCDMA BS to WCDMA BS The Interference TD-SCDMA BS to WCDMA BS, Using the formula : L :needed road loss ,dB; Pe: the equivalent emission power of interfere souse,dBm;GT,e:the antenna emission gain of interfere souse in the interferenced direction,dB;GR,e: the receive gain of interferenced receive antenna in the interference souse direction,dB; It is clealy that the price of PA, GT,e and GR,e are changble in the real situation .here are two situation : The worst situation,the interference souse emission power is largest , receive antenna and emission antenna are face to face,then the antenna emission and receive gain. Pe=PM, GT,e=GT, GR,e=GR.,This situation is rarely in the real situation . Normal situation ,the interference souse emission power is determined by the its cover area .will not be very big , receive antenna and emission antenna are not face to face .To count easly ,we take emission power to be -3dB, receive and emission antenna gains are the biggist gain -3dB.In such situation calculating the road loss and protective distance,when the two system are neighbour or have 5MHz protective band . By study the upper situation ,we have the following conclusion :the frequency distance of TD-SCDMA and WCDMA should be 5MHZ,frequence disposition should like fig.When TD-SCDMA use as macro cover ,to avoid the Interference to WCDMA,the protection band of the frequence DL of TD-SCDMA and WCDMA should be 5MHZ,so TD-SCDMA shoud disposit from #4 frequence,#1,#2 and #3 frequence should not disposit to macro ;If TD-SCMDA use as micro and pico,to insure TD-SCMDA and WCMDA could work well, having the min interference ,#1and #3'frequence should not disposit to TD-SCDMA,that is the two system should have 1.7MHz protective band .Fig TD-SCDMA and WCDMA frequence disposition By calculating the protective band and protective distance of TD-SCDMA å’ŒWCMDA,the text resoved the question of TD-SCDMA and WCMDA conexist in the neighboring frequency band.It is of high value in theory and in practice with 3Gfrequence disposition .
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